The nature of the two oxides of nitrogen,$X$ and $Y$,formed in the reaction of sodium nitrite $(NaNO_2)$ with hydrochloric acid $(HCl)$ is:

There are some deposits of nitrates and phosphates in earth's crust. Nitrates are more soluble in water. Nitrates are difficult to reduce under the laboratory conditions but microbes do it easily. Ammonia forms a large number of complexes with transition metal ions. Hybridization easily explains the ease of sigma donation capability of $NH_3$ and $PH_3$. Phosphine is a flammable gas and is prepared from white phosphorus.
$1.$ Among the following,the correct statement is:
$(A)$ Phosphates have no biological significance in humans
$(B)$ Between nitrates and phosphates,phosphates are less abundant in earth's crust
$(C)$ Between nitrates and phosphates,nitrates are less abundant in earth's crust
$(D)$ Oxidation of nitrates is possible in soil
$2.$ Among the following,the correct statement is:
$(A)$ Between $NH_3$ and $PH_3, NH_3$ is a better electron donor because the lone pair of electrons occupies a spherical '$s$' orbital and is less directional
$(B)$ Between $NH_3$ and $PH_3, PH_3$ is a better electron donor because the lone pair of electrons occupies an $sp^3$ orbital and is more directional
$(C)$ Between $NH_3$ and $PH_3, NH_3$ is a better electron donor because the lone pair of electrons occupies an $sp^3$ orbital and is more directional
$(D)$ Between $NH_3$ and $PH_3, PH_3$ is a better electron donor because the lone pair of electrons occupies a spherical '$s$' orbital and is less directional
$3.$ White phosphorus on reaction with $NaOH$ gives $PH_3$ as one of the products. This is a:
$(A)$ dimerization reaction
$(B)$ disproportionation reaction
$(C)$ condensation reaction
$(D)$ precipitation reaction
Give the answer for questions $1, 2$ and $3.$

Among the members of $V$ $A$ group ($N$,$P$,$As$,$Sb$,and $Bi$),which of the following properties shows an increase as we go down from nitrogen to bismuth?

Ammonia can be dried by

When a lightning flash is produced,which gas is primarily formed?

On heating ammonium dichromate and barium azide separately,we get: